Author Topic: Beating a dead horse.. to DEATH!  (Read 3920 times)


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Beating a dead horse.. to DEATH!
« on: September 12, 2006, 02:49:54 PM »
  The losses (trub, chiller, etc) are only factored into the water calculations and do NOT affect the predicted OG.

  The reason for this is that the standard method for predicting OG is to use only the "theoretical" OG times the overall brewhouse efficiency.  This means that to account for large trub or chiller losses you need to lower your overall brewhouse efficiency.

  This may seem a bit counterintuitive, but if I went with another method such as actually calculating the effects of each system loss then BeerSmith would not be compatible with the other programs and formulas commonly used in brewing.

  I have considered a modification that might "optionally" allow the user to enter their "mash efficiency" instead of brewhouse efficiency and then perform the loss calculations from that point.  This is a possibility for a future release, but I have not yet implemented it.


Hi Brad,

I've been trying to wrap my tiny brain around this really enormous issue and I'm having some trouble.  Hope you can help. ???

I have the same problem as many of these folks.  I usually leave about a gallon or more behind in the kettle, and so my OG is off by a considerable amount, while my gravity into the kettle is spot-on.  It seems I have two choices to address this problem:
1 - Adjust the target amount up by a gallon to cover the losses
2 - Adjust my efficiency down to compensate for the losses

While adjusting the Brewhouse Efficiency seems to be the way to go based on the definition of "Brewhouse Efficiency", this method actually changes the predicted outcome of the product, specifically the color darkens and the IBUs go up.  Common sense tells me that if I brew 6gal and then only put 5gal in the fermenter, that WILL effect the efficiency, but clearly my color and IBUs will not increase.

My question is, which way is best for accurately prdicting the end product?  I'm trying to figure out the best way to compensate for this loss so that when I design a recipe I can predict the outcome as accurately as possible, assuming I don't F it up.

Thanks for your patience,


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Re: Beating a dead horse.. to DEATH!
« Reply #1 on: September 15, 2006, 11:33:00 PM »
  This one has been beat up a bit, but if you want to use the post boil (pre-trub) batch size instead of the current setup, all you need to do is adjust your trub losses to zero and then set your batch size equal to the trub plus final size.  This is equivalent and will give you the pre-trub numbers you are looking for and also allow you to use efficiency numbers that don't include trub loss.

  As also discussed previously, I made a minor correction in the new version (unreleased still) that more properly adjusts for the trub losses when estimating the pre-boil gravity.  I believe this will address your other concern, though again the above method is an equivalent work-around.

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